A previously proposed telescopic damper (energy regenerating damper) for use in a wheel suspension system of a vehicle is configured to convert the kinetic energy of the working fluid which is produced as the piston undergoes a reciprocating movement in the cylinder into electric energy with the aim of contributing to the charging of the onboard battery and reducing the rise in the temperature of the working fluid. More specifically, a rotating member (turbine) is provided in a lower part of the piston and the turbine is connected to a generator rotor of a generator provided in an upper part of the piston via a rod (See Patent Document 1). As the piston along with the piston rod is displaced along the axial direction, the turbine (and hence the generator rotor of the generator) is rotatively actuated by the working fluid, and this produces electric power on the one hand, and reduces the rise in the temperature of the working fluid on the other hand because a smaller part of the kinetic energy is converted into heat.
Patent Document 1: JP UM05-050196A